1. Field of the Invention
The technical field of the invention is that of sub-caliber projectiles and in particular of armor-piercing discarding sabot-type sub-caliber projectiles of a large caliber (caliber greater than 75 mm).
2. Description of the Related Art
Sub-caliber projectiles (or arrow projectiles) are well known. They are constituted of a piercing-material bar, provided with a conical front portion, and carrying a stabilizing fin.
The bar has a caliber much smaller than that of the weapon that fires the projectile (25 to 30 mm diameter bar for a 120 mm caliber weapon).
The shot is made possible by means of a sabot to the caliber of the weapon that releases the bar at the exit of the tube of the weapon.
This conventional configuration allows to obtain a particularly high bar speed (of the order of 1700 m/s for an arrow bar fired by a 120 mm caliber weapon). Patents U.S. Pat. No. 4,724,769 and FR2842897 describe by way of example known arrow projectiles.
The great speed which is communicated to them gives the bars a very high capacity for piercing armors.
One of the main problems encountered by sub-caliber projectiles is that of the perforation reduction related to an impact on the target with an incidence (impact at an angle of the projectile with the target different from 90°).
In fact, known projectiles mostly comprise a head structure comprising one or more piercing nuclei of a diameter smaller than that of the bar itself. Patents U.S. Pat. No. 4,724,769 and FR2578045 show such a conventional head structure.
However, these nuclei located at the head have the effect of causing, upon impacting on a homogeneous target, an enlarged diameter crater which has a choke of a reduced diameter at its entry.
The diameter of the choke is substantially equal to the diameter of the bar while the diameter of the crater may be twice that of the bar.
An oblique impact will therefore cause an interference between the bar and the edge of the choke which results in a disturbance of the bar, thereby reducing its piercing performances.
Furthermore, from patent EP1521052 is known a bomb or missile warhead comprising a penetrating body of a large diameter (greater than 100 mm) and enclosing an explosive charge. This penetrating body carries at its front portion inserts of a dense material (e.g., tungsten alloy) which facilitate the target lock. Such a body is very different from an arrow-type sub-caliber projectile as provided by the invention. It does not comprise a sabot for firing by a weapon tube and its striking velocity on a target is of the order of 500 meters per second. The choke phenomena of the target upon impact do not occur at these reduced velocities.
The arrow sub-caliber projectiles concerned by the invention are fired by a weapon tube by barrel effect and have a striking velocity on a target of about 1700 meters per second.